Method of enabling seamless cobalt gap-fill

ABSTRACT

Methods for depositing a contact metal layer in contact structures of a semiconductor device are provided. In one embodiment, a method for depositing a contact metal layer for forming a contact structure in a semiconductor device is provided. The method comprises performing a cyclic metal deposition process to deposit a contact metal layer on a substrate and annealing the contact metal layer disposed on the substrate. The cyclic metal deposition process comprises exposing the substrate to a deposition precursor gas mixture to deposit a portion of the contact metal layer on the substrate, exposing the portion of the contact metal layer to a plasma treatment process, and repeating the exposing the substrate to a deposition precursor gas mixture and exposing the portion of the contact metal layer to a plasma treatment process until a predetermined thickness of the contact metal layer is achieved.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/145,578, filed May 3, 2016, which is a divisional of U.S. patentapplication Ser. No. 13/786,644, filed Mar. 6, 2013, which claimsbenefit of U.S. Provisional Patent Application No. 61/616,842, filedMar. 28, 2012, each of which is hereby incorporated by reference in itsentirety.

BACKGROUND OF THE INVENTION

Field of the Invention

Embodiments of the invention generally relate to the field ofsemiconductor manufacturing processes, more particularly, to methods fordepositing a contact metal layer in contact structures of asemiconductor device.

Description of the Related Art

Integrated circuits may include more than one million micro-electronicfield effect transistors (e.g., complementary metal-oxide-semiconductor(CMOS) field effect transistors) that are formed on a substrate (e.g.,semiconductor wafer) and cooperate to perform various functions withinthe circuit. Reliably producing sub-half micron and smaller features isone of the key technologies for the next generation of very large scaleintegration (VLSI) and ultra large-scale integration (ULSI) ofsemiconductor devices. However, as the limits of integrated circuittechnology are pushed, the shrinking dimensions of interconnects in VLSIand ULSI technology have placed additional demands on processingcapabilities. Reliable formation of the gate pattern is important tointegrated circuits success and to the continued effort to increasecircuit density and quality of individual substrates and die.

As feature sizes have become smaller, the demand for higher aspectratios, defined as the ratio between the depth of the feature and thewidth of the feature, has steadily increased to 20:1 and even greater. Avariety of problems may occur when depositing contact metal layers intocontact structures with small geometries, such as geometries havingaspect ratios of about 20:1 or smaller. For example, a contact metallayer deposited using a conventional PVD process often suffers from poorstep coverage, overhang, and voids formed within the via or trench whenthe via has a critical dimension of less than 50 nm or has an aspectratio greater than 10:1. Insufficient deposition on the bottom andsidewalls of the vias or trenches can also result in depositiondiscontinuity, thereby resulting in device shorting or poorinterconnection formation. Furthermore, the contact metal layer may havepoor adhesion over the underlying silicon containing layer, resulting inpeeling of the contact metal layer from the substrate and the subsequentconductive metal layer.

With this increase in transistor density and subsequent decrease in thecross-sections of metal-contacts, meeting the contact resistancerequirements using existing low resistivity tungsten (W) integrationschemes has become quite challenging. The necessity of high-resistivityadhesion (e.g., B₂H₆ nucleation) and barrier layers (e.g., TiN) in thetungsten contact integration scheme results in increased contactresistance making it an unattractive option for technology nodes lessthan 22 nanometers.

Therefore, there is a need for an improved method for forming a contactmetal layer in high aspect ratio features.

SUMMARY OF THE INVENTION

Embodiments of the invention generally relate to the field ofsemiconductor manufacturing processes, more particularly, to methods fordepositing a contact metal layer in contact structures of asemiconductor device. In certain embodiments, a method for depositing acontact metal layer for forming a contact structure in a semiconductordevice is provided. The method comprises performing a cyclic metaldeposition process to deposit a contact metal layer on a substrate andannealing the contact metal layer disposed on the substrate. The cyclicmetal deposition process comprises exposing the substrate to adeposition precursor gas mixture to deposit a portion of the contactmetal layer on the substrate, exposing the portion of the contact metallayer to a plasma treatment process, and repeating the exposing thesubstrate to a deposition precursor gas mixture and exposing the portionof the contact metal layer to a plasma treatment process until apredetermined thickness of the contact metal layer is achieved.

In certain embodiments, a method for depositing a contact metal layerfor forming a contact structure in a semiconductor device is provided.The method comprises performing a barrier layer deposition process todeposit a barrier layer on a substrate, performing a wetting layerdeposition to deposit a wetting layer on the substrate, and performing acyclic metal deposition process to deposit a contact metal layer on thesubstrate. The cyclic metal deposition process comprises exposing thesubstrate to a deposition precursor gas mixture to deposit a portion ofthe contact metal layer on the substrate and repeating the exposing thesubstrate to a deposition precursor gas mixture and exposing the portionof the contact metal layer to a plasma treatment process until apredetermined thickness of the contact metal layer is achieved. Themethod further provides for annealing the contact metal layer disposedon the substrate.

In certain embodiments, a method for depositing a contact metal layerfor forming a contact structure in a semiconductor device is provided.The method comprises performing a barrier layer deposition process todeposit a barrier layer on a substrate, performing a wetting layerdeposition process to deposit a wetting layer on the substrate, andperforming an annealing process on the wetting layer. The method furthercomprises performing a metal deposition process to deposit a contactmetal layer on the substrate by exposing the contact metal layer to adeposition precursor gas mixture to deposit a portion of the contactmetal layer on the substrate. Finally, the method comprises exposing theportion of the contact metal layer to a plasma treatment process andannealing the contact metal layer disposed on the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 depicts a sectional view of one embodiment of a metal depositionprocessing chamber suitable for performing embodiments described herein;

FIG. 2 is a schematic top-view diagram of an illustrative multi-chamberprocessing system having the metal deposition processing chamber of FIG.1 incorporated therein;

FIG. 3 depicts a flow diagram for forming a contact metal layer in asemiconductor device in accordance with certain embodiments describedherein;

FIGS. 4A-4E depict cross-sectional views of a semiconductor deviceduring the formation of a contact metal layer manufacture process inaccordance with one embodiment of the present invention; and

FIG. 5 depicts a flow diagram for a cyclic deposition process forforming a contact metal layer in a semiconductor device in accordancewith certain embodiments described herein;

FIG. 6 depicts a flow diagram for forming a contact metal layer in asemiconductor device in accordance with certain embodiments describedherein;

FIGS. 7A-7E depict cross-sectional views of a semiconductor deviceduring the formation of a contact metal layer manufacture process inaccordance with certain embodiments described herein; and

FIG. 8 depicts a flow diagram for forming a contact metal layer in asemiconductor device in accordance with certain embodiments described.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements and features of oneembodiment may be beneficially incorporated in other embodiments withoutfurther recitation. It is to be noted, however, that the appendeddrawings illustrate only exemplary embodiments of this invention and aretherefore not to be considered limiting of its scope, for the inventionmay admit to other equally effective embodiments.

DETAILED DESCRIPTION

Embodiments of the present invention provide gap-fill utilizing metallicCVD processes (e.g., cobalt CVD processes) resulting in a potential lowcontact resistance (Rc) one-material solution for contact fill. The CVDfilms deposited according to embodiments described herein have conformalstep coverage and low surface roughness. Further, the embodimentsdemonstrated herein demonstrate a process for filling contact holes of asemiconductor device with no seam formation.

In one embodiment, a method for depositing a contact metal layer over asubstrate is provided which includes exposing the substrate to a cobaltprecursor gas and hydrogen gas to selectively form a portion of aseamless gap fill cobalt layer within a feature, and exposing the cobaltlayer to a plasma and a reagent, such as nitrogen, ammonia, hydrogen, anammonia/nitrogen mixture, or combinations thereof during apost-treatment process.

As will be explained in greater detail below, a contact metal layer isdeposited on a substrate to form a contact metal structure on thesubstrate. The term “substrate” as used herein refers to a layer ofmaterial that serves as a basis for subsequent processing operations andincludes a surface to be disposed for forming a contact metal layerthereon. The substrate may be a material such as crystalline silicon(e.g., Si<100> or Si<111>), silicon oxide, strained silicon, silicongermanium, doped or undoped polysilicon, doped or undoped siliconwafers, patterned or non-patterned wafers silicon on insulator (SOI),carbon doped silicon oxides, silicon nitride, doped silicon, germanium,gallium arsenide, glass, or sapphire. The substrate can also include oneor more nonconductive materials, such as silicon, silicon oxide, dopedsilicon, germanium, gallium arsenide, glass, and sapphire. The substratecan also include dielectric materials such as silicon dioxide,organosilicates, and carbon doped silicon oxides. Further, the substratecan include any other materials such as metal nitrides and metal alloys,depending on the application.

In one or more embodiments, the substrate can form a gate structureincluding a gate dielectric layer and a gate electrode layer tofacilitate connecting with an interconnect feature, such as a plug, via,contact, line, and wire, subsequently formed thereon. The substrate mayhave various dimensions, such as 200 mm, 300 mm, or 450 mm diameterwafers or other dimensions, as well as rectangular or square panels.Unless otherwise noted, embodiments and examples described herein may beconducted on substrates with a 200 mm diameter, a 300 mm diameter, or a450 mm diameter, particularly a 300 mm diameter.

The term “contact structure” as used herein refers to a layer ofmaterial that includes a contact metal layer that can form part of agate electrode. In one or more embodiments, the contact metal layer canbe nickel layer, cobalt layer, titanium layer or any combinationsthereof.

Moreover, the substrate is not limited to any particular size or shape.The substrate can be a round wafer having a 200 mm diameter, a 300 mmdiameter or other diameters, such as 450 mm, among others. The substratecan also be any polygonal, square, rectangular, curved or otherwisenon-circular workpiece, such as a polygonal glass substrate used in thefabrication of flat panel displays.

Embodiments described herein provide methods for depositing/forming acontact metal layer on a substrate to form a contact structure. Thedeposition process may efficiently improve deposited film step coverage,conformality, and continuity and uniformity across the substrate,thereby improving the overall film properties formed across thesubstrate.

FIG. 1 illustrates a processing chamber 150 that may be used to formcontact metal materials by vapor deposition processes as describedherein. The contact metal materials may contain metallic cobalt,metallic nickel, derivatives thereof, or combinations thereof. Aprocessing chamber 150 may be used to perform CVD, plasma enhanced-CVD(PE-CVD), pulsed-CVD, ALD, PE-ALD, derivatives thereof, or combinationsthereof. Water channels, such as a convolute liquid channel 162, may beused to regulate the temperature of a lid assembly 100 during the vapordeposition process for depositing a cobalt-containing material. In oneembodiment, the lid assembly 100 may be heated or maintained at atemperature within a range from about 100° C. to about 300° C.,preferably, from about 125° C. to about 225° C., and more preferably,from about 150° C. to about 200° C. The temperature is maintained duringthe vapor deposition process of a cobalt-containing material and/ornickel containing material.

A showerhead 156 has a relatively short upwardly extending rim 158screwed to a gas box plate 160. Both the showerhead 156 and the gas boxplate 160 may be formed from or contain a metal, such as aluminum,stainless steel, or alloys thereof. The convolute liquid channel 162 isformed in the top of the gas box plate 160 and covered and sealed by awater cooling cover plate 134. Water is generally flown through theconvolute liquid channel 162. However, alcohols, glycol ethers, andother organic solvents may be used solely or mixed with water totransfer heat away from or to the lid assembly 100. The convolute liquidchannel 162 is formed in a serpentine though generally circumferentialpath having bends (e.g., three sharp U-turns or U-shaped bends) as thepath progresses from the inside to the outside until the path returns tothe inside in a radial channel (not shown). The convolute liquid channel162 is narrow enough to ensure that the flow of water becomes turbulent,thus aiding the flow of heat from the flange of the gas box plate 160 tothe water in the convolute liquid channel 162. A liquid temperatureregulating system (not shown) may be attached to the convolute liquidchannel 162 and used to transfer heat away from or to lid assembly 100.In one example, the lid assembly 100 is configured to be heated ormaintained at a temperature of about 150° C. and is in fluidcommunication with a source of a cobalt precursor, such as dicobalthexacarbonyl butylacetylene “CCTBA,” and a source of a hydrogenprecursor, such as H₂.

The extending rim 158 of the showerhead 156 is attached to the bottomrim 171 of the gas box plate 160. Both rims 158 and 171 are maximallysized between encompassing a lid isolator 175 and an encompassed lowercavity 130 of the showerhead 156. A screw fastening between theshowerhead 156 and the gas box plate 160 ensures good thermal contactover the maximally sized contact area. The thermal flow area extendsfrom the outside at the lid isolator 175 (except for a gap between thelid isolator 175 and either the showerhead 156 or the gas box plate 160)to the inside at a lower cavity 130. The structure of the convoluteliquid channels 162 provides efficient thermal transfer between thewater and the gas box plate 160. The mechanical interface between theflange of gas box plate 160 and showerhead 156 ensures efficient thermaltransfer between the gas box plate 160 and the showerhead 156.Accordingly, cooling of the showerhead 156 is greatly enhanced.

The processing chamber 150 further contains a heater pedestal 152connected to a pedestal stem 154 that may be vertically moved within theprocessing chamber 150. The heater portion of the heater pedestal 152may be formed of a ceramic material. In its upper deposition position,the heater pedestal 152 holds a substrate 402 in close opposition to alower surface 107 of the showerhead 156. A processing region 126 isdefined between the heater pedestal 152 and the lower surface 107 of theshowerhead 156. The showerhead 156 has a plurality of apertures or holes109 communicating between the lower cavity 130 and the processing region126 to allow for the passage of processing gas. The processing gas issupplied through the gas port 132 formed at the center of thewater-cooled gas box plate 160 which is made of aluminum. The upper sideof the gas box plate 160 is covered by a water cooling cover plate 134surrounding the upper portion of the gas box plate 160 that includes agas port 132. The gas port 132 supplies the processing gases to an uppercavity 138 which is separated from the lower cavity 130 by a blockerplate 140. The blocker plate 140 has a large number of holes 109disposed therethrough. In one embodiment, the cavities 130 and 138,showerhead 156, and blocker plate 140 evenly distribute the processinggas over the upper face of the substrate 402.

The substrate 402 may be supported on the heater pedestal 152, which isillustrated in a raised, deposition position. In a lowered, loadingposition, a lifting ring 116 is attached to a lift tube 117 which liftsfour lift pins 118. The lift pins 118 fit to slide into the heaterpedestal 152 so that the lift pins 118 can receive the substrate 402loaded into the chamber through a loadlock port 119 in a chamber body120. In one embodiment, the heater pedestal 152 may contain an optionalconfinement ring 110, such as during plasma-enhanced vapor depositionprocesses.

A side purge gas source 123 may be coupled to the processing chamber 150and configured to supply purge gas to an edge portion 151 of thesubstrate 402 as needed. In one embodiment, the gases may be suppliedfrom the side purge gas source 123 to the substrate 402 edge portion151. The gasses may be a hydrogen gas, argon gas, nitrogen gas, heliumgas, combinations thereof, or the like. Furthermore, a bottom purge gassource 125 may also be coupled to the chamber 150 to supply the purgegas from the bottom of the chamber 150 to the substrate 402 surface.Similarly, the purge gas supplied from the bottom purge gas source 125may include a hydrogen gas, argon gas, nitrogen gas, helium gas,combinations thereof, or the like.

A lid isolator 175 is interposed between showerhead 156 and a lid rim166, which can be lifted off the chamber body 120 to open the processingchamber 150 for maintenance access. The vacuum within processing chamber150 is maintained by a vacuum pump 170 connected to a pump plenum 172within the processing chamber 150, which connects to an annular pumpingchannel 174.

An annular chamber liner 179 made of quartz is disposed in theprocessing chamber 150 which defines a side of the annular pumpingchannel 174 but also partially defines a further choke aperture 181disposed between the processing region 126 and the annular pumpingchannel 174. The annular chamber liner 179 also supports the confinementring 110 in the lowered position of the heater pedestal 152. The chamberliner 179 also surrounds a circumference at the back of the heaterpedestal 152. The chamber liner 179 rests on a narrow ledge in chamberbody 120, but there is little other contact, so as to minimize thermaltransport. Below the chamber liner 179 is located a Z-shaped lowerchamber shield 121, made of opaque quartz. The lower chamber shield 121rests on the bottom of chamber body 120 on an annular boss 177 formed onthe bottom of the lower chamber shield 121. The quartz preventsradiative coupling between the bottom of the heater pedestal 152 and thechamber body 120. The annular boss 177 minimizes conductive heattransfer to the chamber body 120. In an alternative embodiment, thelower chamber shield 121 includes an inwardly extending bottom lipjoined to a conically shaped upper portion conforming to the inner wallof chamber body 120. While this alternative design is operationallysatisfactory, the sloping shape is much more expensive to fabricate inquartz.

In one embodiment, a remote plasma source 141 may be coupled to theprocessing chamber 150 through a gas port 132 to supply reactive plasmafrom the remote plasma source 141 through the plurality of holes 109 inthe showerhead 156 to the processing chamber 150 to the substrate 402surface. It is noted that the remote plasma source 141 may be coupled tothe processing chamber 150 in any suitable position to supply a reactiveremote plasma source to the substrate 402 surface as needed. Suitablegases that may be supplied to the remote plasma source 141 to bedissociated and further delivered to the substrate 402 surface includehydrogen, argon, helium, nitrogen, ammonia, combinations thereof and thelike.

In FIG. 1, a control unit 180 may be coupled to the chamber 150 tocontrol processing conditions. The control unit 180 comprises a centralprocessing unit (CPU) 182, support circuitry 184, and memory 186containing associated control software 183. The control unit 180 may beone of any form of a general purpose computer processor that can be usedin an industrial setting for controlling various chambers andsub-processors. The CPU 182 may use any suitable memory 186, such asrandom access memory, read only memory, floppy disk drive, compact discdrive, hard disk, or any other form of digital storage, local or remote.Various support circuits may be coupled to the CPU 182 for supportingthe chamber 150. The control unit 180 may be coupled to anothercontroller that is located adjacent individual chamber components.Bi-directional communications between the control unit 180 and variousother components of the chamber 150 are handled through numerous signalcables collectively referred to as signal buses, some of which areillustrated in FIG. 1.

FIG. 2 is a schematic top view diagram of an illustrative multi-chamberprocessing system 200 that can be adapted to perform a metal layerdeposition process as disclosed herein having a processing chamber 80,such as the chamber 150 described above in reference to FIG. 1,integrated therewith. The system 200 can include one or more load lockchambers 202 and 204 for transferring substrates 90 into and out of thesystem 200. Generally, the system 200 is maintained under vacuum and theload lock chambers 202 and 204 can be “pumped down” to introducesubstrates 90 introduced into the system 200. A first robot 210 cantransfer the substrates 90 between the load lock chambers 202 and 204,and a first set of one or more substrate processing chambers 212, 214,216, and 80. Each processing chamber 212, 214, 216, and 80 is configuredto be at least one of a substrate deposition process, such as cyclicallayer deposition (CLD), atomic layer deposition (ALD), chemical vapordeposition (CVD), physical vapor deposition (PVD), etch, degas,pre-cleaning orientation, anneal, and other substrate processes.Furthermore, one of the processing chamber 212, 214, 216, and 80 mayalso be configured to perform a pre-clean process prior to performing adeposition process or a thermal annealing process on the substrate 90.The position of the processing chamber 80 utilized to perform a thermalannealing process relative to the other chambers 212, 214, 216 is forillustration, and the position of the processing chamber 80 may beoptionally be switched with any one of the processing chambers 212, 214,216 if desired.

The first robot 210 can also transfer substrates 90 to/from one or moretransfer chambers 222 and 224. The transfer chambers 222 and 224 can beused to maintain ultrahigh vacuum conditions while allowing substrates90 to be transferred within the system 200. A second robot 230 cantransfer the substrates 90 between the transfer chambers 222 and 224 anda second set of one or more processing chambers 232, 234, 236 and 238.Similar to the processing chambers 212, 214, 216, and 80, the processingchambers 232, 234, 236, and 238 can be outfitted to perform a variety ofsubstrate processing operations including the dry etch processesdescribed herein in addition to cyclical layer deposition (CLD), atomiclayer deposition (ALD), chemical vapor deposition (CVD), physical vapordeposition (PVD), etch, pre-clean, degas, and orientation, for example.Any of the substrate processing chambers 212, 214, 216, 232, 234, 236,and 238 can be removed from the system 200 if not necessary for aparticular process to be performed by the system 200. After thepreclean, deposition and/or a thermal annealing process is performed inthe processing chamber 80, the substrate may further be transferred toany of the processing chambers 212, 214, 216, 232, 234, 236, and 238 ofthe system 200 to perform other process as needed.

FIG. 3 illustrates a flow diagram of one embodiment of a processsequence 300 used to deposit a contact metal layer in a semiconductordevice structure on a substrate. The sequence described in FIG. 3corresponds to the fabrication stages depicted in FIGS. 4A-4E, which arediscussed below. FIGS. 4A-4E illustrate schematic cross-sectional viewsof a substrate 402 having a device structure 408 formed thereon duringdifferent stages of fabricating a contact metal layer 420 on the devicestructure 408 illustrated by the processing sequence 300. The sequenceof FIG. 3 is generally provided with reference to a CVD, ALD, or PVDdeposited cobalt contact metal layer.

Possible integration schemes include but are not limited to: (a) PVDTi+ALD TiN; (b) PVD Ti+CVD Co; (c) CVD Co; and (d) CVD Co+PVD Co. PVD Tiprovides good electrical contact with underlying silicide at source ordrain. ALD TiN improves adhesion of the cobalt film, if needed to helpre-flow of the cobalt film. CVD Co: cobalt fill using CVD films or CVDfollowed by re-flow.

The process sequence 300 starts at block 310 by providing a substrate,such as the substrate 402 depicted in FIG. 4A, into the processingchamber, such as the substrate 402 disposed in the processing chamber150 depicted in FIG. 1, or other suitable processing chamber. Thesubstrate 402 shown in FIG. 4A includes a semiconductor device structure408 (e.g., such as a gate structure or other structures configured toform a contact structure) formed on the substrate 402. It is noted thatthis particular device structure 408 may be used in three-dimensional(3-D) flash memory applications, DRAM applications, or other suitableapplications with high aspect ratio or other odd geometries.

A silicon containing layer 404 is formed on the substrate 402 havingopenings 406 formed therein with high aspect ratios, such as aspectratios greater than 10:1, for example about greater than 20:1. Theopenings 406 (which may be a contact opening, contact via, contacttrench, contact channel or the like) are formed in the device structure408 and have sidewalls 412 and a bottom 414 which form an open channelto expose the underlying silicon containing layer 404. The siliconcontaining layer 404 may include any suitable layers such as a singlesilicon layer or a multiple layer film stack having at least one siliconcontaining layer formed therein. In the embodiment wherein the siliconcontaining layer 404 is in the form of a single layer, the siliconcontaining layer 404 may be a silicon oxide layer, an oxide layer, asilicon nitride layer, a nitride layer, a silicon oxynitride layer, atitanium nitride layer, a polysilicon layer, a microcrystalline siliconlayer, a monocrystalline silicon, a doped polysilicon layer, a dopedmicrocrystalline silicon layer, or a doped monocrystalline silicon.

In another example, the silicon containing layer 404 may be a film stackincluding a composite oxide and nitride layer, at least one or moreoxide layers sandwiching a nitride layer, and combinations thereof.Suitable dopants doped in the silicon containing layer 404 may includep-type dopants and n-type dopants, such as boron (B) containing dopantsor phosphine (P) containing dopants. In one embodiment wherein thesilicon containing layer 404 is in form of a multiple film stack havingat least one silicon containing layer, the silicon containing layer 404may include repeating pairs of layers including a silicon containinglayer and a dielectric layer. In one embodiment, the silicon containinglayer 404 may include a polysilicon layer and/or other metal materialsand/or a dielectric layer disposed therein. Suitable examples of thedielectric layer may be selected from a group consisting of an oxidelayer, silicon oxide layer, a silicon nitride layer, a nitride layer,titanium nitride layer, a composite of oxide and nitride layer, at leastone or more oxide layers sandwiching a nitride layer, and combinationsthereof, among others.

Prior to transferring the substrate 402 into the metal depositionprocessing chamber described at block 310, a pre-cleaning process isoptionally performed to treat the substrate surfaces 411, sidewalls 412and bottoms 414 of the openings 406 to remove native oxides or othersources of contaminants. Removal of native oxides or other sources ofcontaminants from the substrate 402 may provide a low contact resistancesurface to form a good contact surface for forming a contact metallayer.

The pre-cleaning process performed includes supplying a pre-cleaning gasmixture into a pre-cleaning chamber. The pre-cleaning chamber may be aPreclean PCII, PCXT or Siconi™ chambers which are available from AppliedMaterials, Inc., Santa Clara, Calif. The pre-cleaning chamber may beincorporated in the illustrative multi-chamber processing system 200 andmay be configured to be one of the processing chamber 212, 214, 216,232, 234, 236, 238 of the system 200 as needed. It is noted that otherpre-cleaning chambers available from other manufactures may also beutilized to practice the embodiments described herein.

The pre-cleaning process is performed by supplying a cleaning gasmixture into the pre-cleaning processing chamber incorporated in thesystem 200 to form a plasma from the pre-cleaning gas mixture forremoving the native oxide. In one embodiment, the pre-cleaning gasmixture used to remove native oxides is a mixture of ammonia (NH₃) andnitrogen trifluoride (NF₃) gases. The amount of each gas introduced intothe processing chamber may be varied and adjusted to accommodate, forexample, the thickness of the native oxide layer to be removed, thegeometry of the substrate being cleaned, the volume capacity of theplasma, the volume capacity of the chamber body, as well as thecapabilities of the vacuum system coupled to the chamber body.

In one or more embodiments, the gases added to provide a pre-cleaninggas mixture having at least a 1:1 molar ratio of ammonia (NH₃) tonitrogen trifluoride (NF₃). In one or more embodiments, the molar ratioof the pre-cleaning gas mixture is at least about 3:1 (ammonia tonitrogen trifluoride). The gases are introduced at a molar ratio of fromabout 5:1 (ammonia to nitrogen trifluoride) to about 30:1. In yetanother embodiment, the molar ratio of the gas mixture is from about 5:1(ammonia to nitrogen trifluoride) to about 10:1. The molar ratio of thepre-cleaning gas mixture can also fall between about 10:1 (ammonia tonitrogen trifluoride) and about 20:1.

A purge gas or carrier gas can also be added to the pre-cleaning gasmixture. Any suitable purge/carrier gas can be used, such as argon,helium, hydrogen, nitrogen, or mixtures thereof. The overallpre-cleaning gas mixture is from about 0.05% to about 20% by volume ofammonia and nitrogen trifluoride. The remainder of the pre-cleaning gasmixture may be the purge/carrier gas.

The operating pressure within the pre-clean chamber can be varied. Thepressure may be maintained between about 1 Torr and about 10 Torr. A RFsource power may be applied to maintain a plasma in the cleaning gasmixture. For example, a power of about 15 Watts to about 100 Watts maybe applied to maintain a plasma inside the pre-cleaning processingchamber. The frequency at which the power is applied is about 350 kHz.The frequency can range from about 50 kHz to about 350 kHz. The plasmaenergy dissociates the ammonia and nitrogen trifluoride gases intoreactive species, e.g., fluorine radicals and/or hydrogen radicals thatcombine to form a highly reactive ammonia fluoride (NH₄F) compoundand/or ammonium hydrogen fluoride (NH₄F.HF) in the gas phase. Thesemolecules are then delivered from the plasma location to the substratesurface to be cleaned. A purge/carrier gas can be used to facilitate thedelivery of the reactive species to the substrate. In one embodiment, atitanium layer may be deposited after the pre-cleaning process. Thetitanium layer operates to gather any remaining oxygen at the interfaceof the via and the underlying substrate which provides for improvedelectrical contact with the underlying substrate.

At block 320, prior to deposition of a contact metal layer on thesubstrate 402, but after the substrate 402 is provided in the metaldeposition processing chamber 150 at block 310, a pretreatment processmay be performed to pre-treat the substrate surface 411, thus, forming atreated surface region 410 on the surface 411, sidewalls 412 and bottoms414 of the openings 406 in the silicon containing layer 404, as shown inFIG. 4B. In certain embodiments, the substrate surface 411 may have someweak or residual dangling bonding structures of Si—F, N—F, H—F, and Si—Non the substrate surface left from the optional pre-cleaning processpreviously performed on the substrate 402. The dangling bonds mayundesirably and adversely obstruct absorption or adherence of metallicatoms deposited on the substrate surface in the subsequent contact metaldeposition process. Thus, the pretreatment process at block 320 may beperformed to efficiently alter the surface bonding structure of thesurface 411 of the silicon containing layer 404, thereby providing asurface having a good absorption ability to promote adherence ofmetallic atoms provided from the subsequent contact metal depositionprocess. It is believed that the pretreatment process may efficientlyconvert or remove the bonding structure of Si—F, H—F, N—F, and Si—N,into the bonding of Si—H or Si—Si, which may assist in the adherence ofthe metallic atoms to form a layer thereon.

In one embodiment, a pre-treatment gas mixture may be supplied into themetal deposition processing chamber 150 to alter the surface propertiesof the substrate 402 prior to the contact metal deposition process. Inone embodiment, the pre-treatment gas mixture may include at least ahydrogen containing gas, such as H₂, H₂O, H₂O₂, or the like. An inertgas, such as Ar, He, Kr, and the like, may also be supplied into thepre-treatment gas mixture. Additionally, a nitrogen containing gas, suchas N₂, NH₃, N₂O, NO₂, and the like, may also be supplied into thepre-treatment gas mixture. In an exemplary embodiment, the pre-treatmentgas mixture supplied to pre-treat the substrate surface 411 includes ahydrogen containing gas, such as a H₂ gas, and an inert gas, such as Argas. In another exemplary embodiment, the pre-treatment gas mixturesupplied to pre-treat the substrate surface 411 includes a hydrogencontaining gas, such as a H₂ gas, an inert gas, such as Ar gas, and anitrogen containing gas, such as a NH₃ gas.

The pre-treatment gas mixture may be supplied from a remote plasmasource, such as the remote plasma source 141 coupled to the metaldeposition processing chamber 150, to supply the pre-treatment gasmixture plasma remotely from the processing chamber 150 to the substratesurface 411. Alternatively, the pre-treatment gas mixture may besupplied from any other suitable sources installed in the processingchamber 150 to the substrate surface 411.

During the pretreatment process at block 320, several process parametersmay be regulated to control the pretreatment process. In one exemplaryembodiment, a process pressure in the metal deposition processingchamber 150 is regulated between about 50 mTorr to about 5000 mTorr,such as between about 500 mTorr and about 1000 mTorr, for example, atabout 700 mTorr. An RF source power may be applied to maintain a plasmain the pretreatment gas mixture. For example, a power of about 1000Watts to about 6000 Watts may be applied to maintain a plasma inside theprocessing chamber 150. The hydrogen containing gas supplied in thepretreatment gas mixture may be flowed into the processing chamber 150at a rate between about 400 sccm to about 4000 sccm and the inert gassupplied in the pretreatment gas mixture may be flowed at a rate betweenabout 200 sccm and about 2000 sccm. The nitrogen containing gas suppliedin the pretreatment gas mixture may be flowed at a rate between about100 sccm and about 3000 sccm. A temperature of the substrate 402 ismaintained between about 125 degrees Celsius to about 250 degreesCelsius. In one embodiment, the substrate 402 is subjected to thepretreatment process for between about 10 seconds to about 2 minutes,depending on the operating temperature, pressure, and flow rate of thegas. For example, the substrate 402 can be exposed for about 30 secondsto about 60 seconds. In an exemplary embodiment, the substrate isexposed for about 40 seconds or less.

Optionally, at block 330 a barrier layer deposition process may beperformed to deposit a barrier layer 416 on the substrate, as shown inFIG. 4C. The barrier layer 416 generally prevents diffusion of thecontact metal layer to the junction material on the substrate, typicallya silicon or silicon germanium compound. The barrier layer generallycontains a metal or a metal nitride material, such as titanium (Ti),titanium nitride (TiN), alloys thereof, or combinations thereof. Thebarrier layer 416 may also comprise plasma nitrided (N₂ or NH₃) Ti andPVD Cobalt. If the barrier layer 416 comprises a nitrided Ti layer, onlythe top few angstroms of titanium are converted to a TiN compound. Ithas been found that both oxidized and non-oxidized Ti and TiN barrierlayers provide for improved diffusion resistance. The barrier layer 416may have a thickness within a range from about 2 Å to about 100 Å, morenarrowly within a range from about 3 Å to about 80 Å, more narrowlywithin a range from about 4 Å to about 50 Å, more narrowly within arange from about 5 Å to about 25 Å, more narrowly within a range fromabout 5 Å to about 20 Å, more narrowly within a range from about 5 Å toabout 15 Å, and more narrowly within a range from about 5 Å to about 10Å. The barrier layer is generally deposited by atomic layer deposition(ALD), plasma-enhanced ALD (PE-ALD), chemical vapor deposition (CVD), orphysical vapor deposition (PVD) processes.

The barrier layer 416 is similar to a wetting layer which is describedin detail below. The barrier layer 416, as described above, generallyprevents diffusion of the contact metal layer to the junction materialon the substrate. A wetting layer generally enhances the adherence ofthe contact metal layer, Cobalt in some embodiments, which reduces theformation of undesirable voids in the features during annealingprocesses performed on the contact metal layer.

At block 340, after the pre-treatment process of block 320 is performedon the substrate surface to form the treated surface region 410 ordeposition of the barrier layer 416 in block 330, a CVD contact metaldeposition process may be performed in the processing chamber 150 todeposit a contact metal layer 420, as shown in FIG. 4D. The contactmetal layer 420 may be deposited using the cyclic deposition processdescribed in FIG. 5. The contact metal layer 420 fills the opening 406.Suitable examples of the contact metal layer 420 include titanium (Ti),cobalt (Co), nickel (Ni), alloys thereof, or any combination thereof. Inone particular embodiment described therein, the contact metal layer 420deposited on the substrate 402 is a cobalt (Co) layer.

The contact metal layer 420 may be deposited using a multi-stepdeposition process comprising multiple cycles of performing a cyclicmetal deposition process to deposit the contact metal layer 420 followedby annealing the contact metal layer 420. In certain embodiments, thethickness of the contact metal layer 420 should be less than 50% of thefeature diameter (critical dimension) of the smallest feature to befilled. For example, the cyclic metal deposition process is performed topartially fill a feature to less than half of the feature diameterfollowed by an anneal process. The cyclic deposition process followed byan anneal would then be repeated to deposit until the contact metallayer 420 achieved a predetermined thickness. In an alternativeembodiment, the contact metal layer 420 may be deposited to completelyfill the feature in a single, non-cyclic deposition process. In thisembodiment, the contact metal layer 420 is then annealed. The non-cycliccontact metal layer 420 deposition process and subsequent annealprocesses increase throughput because they require less time tocomplete.

FIG. 5 depicts a flow diagram for a cyclic deposition process as shownin block 340 for forming a contact metal layer, such as contact metallayer 420, in a semiconductor device in accordance with one embodimentof the present invention. In one embodiment, process includes exposing asubstrate to a deposition gas to form a portion of a contact metal layer(block 510), optionally purging the deposition chamber (block 520),exposing the substrate to a plasma treatment process (block 530),optionally purging the deposition chamber (block 540), and determiningif a predetermined thickness of the cobalt contact metal layer has beenachieved (block 550). In one embodiment, the cycle of blocks 510-550 maybe repeated if the cobalt contact metal layer has not been formed havingthe predetermined thickness. Alternately, the process may be stoppedonce the contact metal layer has been formed having the predeterminedthickness.

During the contact metal deposition process, the contact metal layer 420may be formed or deposited by introducing a deposition precursor gasmixture including a cobalt precursor or a nickel precursorsimultaneously with, sequentially with, or alternatively without areducing gas mixture (reagent), such as a hydrogen gas (H₂) or a NH₃gas, into the metal deposition processing chamber 150 during a thermalCVD process, a pulsed-CVD process, a PE-CVD process, a pulsed PE-CVDprocess, or a thermal ALD process. Additionally, the depositionprecursor gas mixture may also include a purge gas mixture suppliedconcurrently into the processing chamber for processing. In anotherembodiment, the contact metal layer 420 may be formed or deposited bysequentially repetitively introducing a pulse of the depositionprecursor gas mixture, such as a cobalt precursor, and a pulse of areducing gas mixture, such as a hydrogen gas (H₂) or a NH₃ gas, into themetal deposition processing chamber 150 during a thermal ALD process ora pulsed PE-CVD process. In another embodiment, the contact metal layer420 may be formed or deposited by continuously flowing the reducing gasmixture, such as a hydrogen gas (H₂) or a NH₃ gas, while repetitivelyintroducing a pulse of the deposition precursor gas mixture, such as acobalt precursor, and a pulse of a reducing gas mixture into the metaldeposition processing chamber 150 during a thermal ALD process or apulsed PE-CVD process. In another embodiment, the contact metal layer420 may be formed or deposited by continuously flowing the reducing gasmixture, such as a hydrogen gas (H₂) or a NH₃ gas, and the depositionprecursor gas mixture, such as a cobalt precursor, under plasmaconditions during a PE-CVD process. In another embodiment, the contactmetal layer 420 may be formed or deposited by continuously flowing thereducing gas mixture, such as a hydrogen gas (H₂) or a NH₃ gas underplasma conditions and periodically pulsing the deposition precursor gasmixture, such as a cobalt precursor during a PE-CVD process.

Suitable cobalt precursors for forming cobalt-containing materials(e.g., metallic cobalt or cobalt alloys) by CVD or ALD processesdescribed herein include cobalt carbonyl complexes, cobalt aminidatecompounds, cobaltocene compounds, cobalt dienyl complexes, cobaltnitrosyl complexes, derivatives thereof, complexes thereof, plasmathereof, or combinations thereof. In some embodiments, cobalt materialsmay be deposited by CVD and ALD processes further described in commonlyassigned U.S. Pat. No. 7,264,846 and U.S. Ser. No. 10/443,648, filed May22, 2003, and published as US 2005-0220998, both of which are hereinincorporated by reference in their entirety.

Suitable cobalt precursors may include, but not limited to, cobaltcarbonyl complexes, cobalt aminidate compounds, cobaltocene compounds,cobalt dienyl complexes, cobalt nitrosyl complexes, cobalt diazadienylcomplexes, cobalt hydride complexes, derivatives thereof, complexesthereof, plasmas thereof, or combinations thereof. In one embodiment,examples of the cobalt precursors that may be used herein includedicobalt hexacarbonyl butylacetylene (CCTBA, (CO)₆Co₂(HC≡C^(t)Bu)),dicobalt hexacarbonyl methylbutylacetylene ((CO)₆Co₂(MeC≡C^(t)Bu)),dicobalt hexacarbonyl phenylacetylene ((CO)₆Co₂(HC≡CPh)), dicobalthexacarbonyl methylphenylacetylene ((CO)₆Co₂(MeC≡CPh)), dicobalthexacarbonyl methylacetylene ((CO)₆Co₂(HC≡CMe)), dicobalt hexacarbonyldimethylacetylene ((CO)₆Co₂(MeC≡CMe)), cobalt aminidate (C₂₀H₄₂CoN),cobalt hexafluoro acetylacetone (Co(C₅HF₆O₂)₂.xH₂O), cobaltacetylacetonate ((CH₃COC═COCH₃)₃Co), cobalt (II) acetylacetone((CH₃COC═COCH₃)₂Co), cobalt acetate((CH₃COO)₂Co), derivatives thereof,complexes thereof, plasmas thereof, or combinations thereof. Otherexemplary cobalt carbonyl complexes include cyclopentadienyl cobaltbis(carbonyl) (CpCo(CO)₂), tricarbonyl allyl cobalt((CO)₃Co(CH₂CH═CH₂)), cobalt tricarbonyl nitrosyl (Co(CO)₃NO),derivatives thereof, complexes thereof, plasmas thereof, or combinationsthereof. In one particular example of the cobalt precursors used hereinis dicobalt hexacarbonyl butylacetylene (CCTBA, (CO)₆Co₂(HC≡C^(t)Bu)).It is noted that the dicobalt hexacarbonyl butylacetylene (CCTBA,(CO)₆Co₂(HC≡C^(t)Bu)) precursor may be supplied into the metaldeposition processing chamber 150 with a carrier gas, such as a Ar gas.

Examples of the alternative reagents (i.e., reducing agents used withcobalt precursors for forming the cobalt materials during the depositionprocess as described herein may include hydrogen (e.g., H₂ or atomic-H),nitrogen (e.g., N₂ or atomic-N), ammonia (NH₃), hydrazine (N₂H₄), ahydrogen and ammonia mixture (H₂/NH₃), borane (BH₃), diborane (B₂H₆),triethylborane (Et₃B), silane (SiH₄), disilane (Si₂H₆), trisilane(Si₃H₈), tetrasilane (Si₄H₁₀), methyl silane (SiCH₆), dimethylsilane(SiC₂H₈), phosphine (PH₃), derivatives thereof, plasmas thereof, orcombinations thereof. In one particular example, the reagents orreducing agents used herein is ammonia (NH₃).

During the cyclic deposition process at block 340, in between each pulseof the deposition precursor gas mixture and the plasma pretreatmentprocess, a purge gas mixture may be supplied from a side/edge and/or abottom of the processing chamber 150 in between each or selecteddeposition precursor pulses to the edge portion 151 of the substrate402. The purge gas mixture may be supplied from the side and/or bottompurge gas source 123 and 125 disposed in the processing chamber 150 tosupply the purge gas mixture to an edge/periphery of the substrate 402surface. It is noted that the edge/periphery region of the substrate 402as described herein may refer to a substrate 402 edge region betweenabout 1 mm and about 5 mm from the substrate edge/bevel for a 300 mmsubstrate or between about 145 mm and about 149 mm from the substratecenter point/center line (e.g. a diameter passing through the substratecenter point). It should also be understood that gas flows during theplasma treatment process of block 530 may also serve to purge theprocess chamber.

In one embodiment, the purge gas mixture supplied in the contact metaldeposition process may include at least a hydrogen containing gas and aninert gas. It is noted that the purge gas mixture may be supplied withthe deposition precursor gas mixture during the deposition process asneeded. Suitable examples of the hydrogen containing gas may include H₂,H₂O, H₂O₂ or the like. Suitable examples of the inert gas include Ar,He, or Kr. In one particular embodiment, the purge gas mixture suppliedduring the metal deposition process may include H₂ and Ar gas.

In one embodiment of the deposition process, a pulse of the depositionprecursor gas mixture along with a reducing gas and optionally apurge/carrier gas mixture is supplied to the deposition chamber 150. Theterm pulse as used herein refers to a dose of material injected into theprocess chamber. The pulse of the deposition precursor gas mixturecontinues for a predetermined time interval. Between each pulse of thedeposition precursor gas mixture and the plasma treatment process, thepurge gas mixture may be pulsed into the processing chamber in betweeneach or multiple pulses of the deposition precursor gas mixture toremove the impurities or residual precursor gas mixture which isunreacted/non-absorbed by the substrate 402 surface (e.g., unreactedcarbon containing impurities from the cobalt precursor or others) sothey may be pumped out of the processing chamber.

The time interval for the pulse of the deposition precursor gas mixtureis variable depending on a number of factors such as, film thicknessrequirement, process chamber volume, throughput concern, gas flow rate,and the like. In one embodiment, the process conditions areadvantageously selected so that a pulse of the deposition precursor gasmixture provides a sufficient amount of precursor, such that at least amonolayer of the cobalt metal precursor is adsorbed on the substrate402. Thereafter, excess cobalt metal precursor remaining in the chambermay be removed from the processing chamber and pumped out by the purgegas mixture.

In some embodiments, the reducing gas mixture may be suppliedconcurrently with the deposition precursor gas mixture in a single pulseto form the contact metal layer 416. In one embodiment depicted herein,the pulse of the reducing gases may be co-flowed with the depositionprecursor gas mixture after a first few pulses, such as between first tofifth pulses, of the deposition precursor gas mixture.

In operation at block 510, a first pulse of the deposition precursor gasmixture is pulsed into the processing chamber 150 to deposit a portionof the cobalt contact metal layer 420 on the substrate. Each pulse ofthe deposition precursor gas mixture into the processing chamber 150 maydeposit a cobalt layer having a thickness between about 5 Å and about100 Å. During pulsing of the deposition precursor gas mixture, severalprocess parameters are also regulated. In one embodiment, the processpressure is controlled at between about 7 Torr and about 30 Torr. Theprocessing temperature is between about 125 degrees Celsius and about250 degrees Celsius. For plasma enhanced processes, the RF power may becontrolled at between about 100 Watts and about 1200 Watts. The cobaltgas precursor supplied in the deposition precursor gas mixture may becontrolled at between about 1 sccm and about 10 sccm. The reducing gas,such as the H₂ gas, may be supplied at between about 100 sccm and about10,000 sccm, such as between about 3000 sccm to about 5000 sccm. The H₂gas supplied from the substrate edge/substrate bottom may be controlledat between about 200 sccm and about 1000 sccm. Argon gas may be suppliedfrom the substrate edge/substrate bottom at between about 200 sccm andabout 1000 sccm.

Optionally, after block 510, the process chamber may be purged. Afterpulsing of the deposition precursor gas mixture, a purge gas mixture isthen supplied into the processing chamber to purge out the residuals andimpurities from the processing chamber. During pulsing of the purge gasmixture, the process pressure may be pumped down to a certain low level,such as lower than 2 Torr, for example lower than 0.5 Torr, at arelatively short time interval, such as between about 1 seconds andabout 5 seconds, so as to assist rapidly pumping out the residuals andimpurities from the processing chamber. Several process parameters arealso regulated during pulsing of the purge gas mixture. In oneembodiment, the process pressure is controlled at between about 0.1 Torrand about 2 Torr, such as 0.1 Torr and about 1 Torr, for example betweenabout 0.1 Torr and about 0.6 Torr. The processing temperature is betweenabout 125 degrees Celsius and about 250 degrees Celsius. The RF powermay be controlled at between about 100 Watts and about 800 Watts. The H₂gas supplied in the purge gas mixture may be controlled at between about200 sccm and about 1000 sccm. The Ar gas may be supplied at betweenabout 200 sccm and about 1000 sccm.

Subsequent to either exposing the substrate 402 to a deposition gas atblock 510 or purging the deposition chamber at block 520 the substrate402 is exposed to a plasma treatment process. The plasma treatmentprocess reduces surface roughness and improves the resistivity of the asdeposited portion of the cobalt contact metal layer 420. Exemplaryplasma forming gases include hydrogen (H₂), nitrogen (N₂), ammonia(NH₃), and combinations thereof. During the plasma treatment process,several process parameters are also regulated. In one embodiment, theprocess pressure is controlled at between about 7 Torr and about 30Torr. The processing temperature is between about 125 degrees Celsiusand about 250 degrees Celsius. The RF power may be controlled at betweenabout 100 Watts and about 800 Watts, for example, about 400 Watts. Theplasma forming gas, such as H₂ gas, may be supplied at between about3000 sccm and about 5000 sccm, for example, about 4000 sccm. The H₂ gassupplied from the substrate edge/substrate bottom may be controlled atbetween about 200 sccm and about 1000 sccm. The Ar gas may be suppliedfrom the substrate edge/substrate bottom at between about 200 sccm andabout 1000 sccm.

It has been shown that the plasma treatment either during deposition orafter deposition helps reduce the surface roughness of the as-depositedfilm and helps reduce carbon impurities in the as-deposited film. Thus,H radical life time, especially inside the narrow (<15 nm criticaldimension and >5 aspect ratio) via and trench structures expected fortransistor technology node ≤14 nm, is an important parameter to enableseamless and void-free cobalt gap fill. The life time of the H radicalinside the chamber during a CVD process can be improved by flowing aninert gas, such as He, Ne, Ar, among others, during the plasma treatmentusing an inductively coupled plasma source, microwave plasma source, ore-beam plasma source. The plasma sources are available from AppliedMaterials, Inc. or other vendors.

Subsequent to exposing the substrate to a plasma treatment process inblock 530, the deposition chamber may optionally be purged in block 540.The optional purge of block 540 may be performed similarly to the purgeprocess described in block 520.

At block 550, if the predetermined thickness of the contact metal layer420 has not been achieved, additional cycles starting from exposing thesubstrate to the deposition precursor gas mixture followed with theplasma pretreatment process can then be repeatedly performed until adesired thickness range of the contact metal layer 420 is reached. Ifthe predetermined thickness of the contact metal layer has beenachieved, the process proceeds to block 350 where a thermal annealingprocess is performed.

For example, if the total thickness of the contact metal layer is 10 nmand the portion of the contact layer is deposited at 2 nm/cycle then 5cycles of (2 nm deposition followed by plasma treatment) will be needed.

At block 350, a thermal annealing process is performed in a thermalannealing chamber on the substrate 402 to improve the properties of thecontact metal layer 420. The thermal annealing chamber may be one of thechambers processing chamber 212, 214, 216, 232, 234, 236, 238 of thesystem 200 as needed. In one embodiment, the thermal annealing processperformed at block 350 may have a temperature range between about 200degrees Celsius and about 1400 degrees Celsius, such as between about200 degrees Celsius and about 500 degrees Celsius. During the thermalannealing process, a gas mixture including at least a hydrogencontaining gas and/or an inert gas (e.g., argon) is supplied into theannealing chamber. The gas mixture may be supplied to the annealingchamber using either a static process where the chamber is filled withgas prior to the anneal process or a continuous flow process where thegas mixture is continuously flowed through the annealing chamber duringthe anneal process.

In one embodiment, the thermal annealing process at 350 may be performedby supplying a gas mixture including at least one of a hydrogencontaining gas, an inert gas, and a nitrogen containing as into theannealing chamber at a flow rate between about 100 sccm and about 2000sccm, controlling a chamber pressure of about 0.5 Torr and about 15Torr, for example, between about 5 Torr and about 8 Torr, maintaining atemperature range between about 150 degrees Celsius and about 500degrees Celsius, for example, between about 300 degrees Celsius andabout 475 degrees Celsius, and performing the thermal annealing process,optionally while rotating the substrate, for between about 30 secondsand about 600 seconds. Suitable examples of gases for the gas mixturesupplied in the thermal annealing chamber may include a hydrogen gas, anitrogen containing gas, an inert gas (e.g., argon) or other gases asneeded. In one embodiment, the gas mixture supplied into the processingchamber to perform the silicidation process includes hydrogen gas (H₂)supplied at a flow ratio between about 1:10 and about 1:1, such as about1:3.

An example of a suitable thermal processing chamber, in which block 350may be performed, is a dual mode degas (DMD) chamber, available fromApplied Materials, Inc. Other examples of suitable thermal processingchambers are the Vantage® Vulcan™ RTP chamber and the Vantage® Astra™DSA chamber. It should be noted that the annealing process may notnecessarily be integrated with the contact metal layer 420 depositionchamber. The use of RTP and DSA anneal may provide for further controlof temperature uniformity and rapid temperature change. It is noted thatother thermal annealing chamber available from other manufactures mayalso be utilized to practice the present invention.

After the thermal annealing process is completed, at block 360, if thepredetermined thickness of the contact metal layer 420 has not beenachieved, additional cycles starting from performing a cyclic metaldeposition to deposit a contact metal layer at block 340 followed byperforming an annealing process on the contact metal layer at block 350can then be repeatedly performed until a desired thickness range of thecontact metal layer 420 is reached. If the predetermined thickness ofthe contact metal layer has been achieved, the process is complete andadditional processing steps may be performed.

Thus, according to the aforementioned embodiments, methods fordepositing a contact metal layer in a contact structure are provided.The methods include filling contact holes with seamless contact metallayers by annealing the as-deposited contact metal layers. Annealing ofCVD cobalt films results in a bottom-up, seamless gap fill. In certainembodiments, a wetting layer is not required for reflow of cobalt.Thickness of the contact metal layer (e.g., CVD cobalt layer) may beless than 50% of the feature diameter (critical dimension). A cyclicprocess utilizing a combination of thin cobalt film deposition andshort-time anneal is used. Ambience during the short-time anneal lowersthe required anneal temperature to achieve seamless cobalt fill. Ablanket wafer study demonstrates 50% reduction in resistivity of cobaltfilms after the anneal treatment. Variations of anneal time,temperature, atmosphere (type of gas used), static gas pressure or gasflow during the anneal step may be used to reduce roughness and improvethe resistivity of the contact metal layer. Short anneal time (e.g., 1minute) is sufficient to reduce cobalt resistivity and roughness. Gasflow during anneal further improves the resistivity of cobalt films.Argon and hydrogen gas or a combination of both may be used for annealatmosphere. PVD cobalt can be utilized in place of CVD cobalt. Acombination of CVD & PVD can also be utilized where CVD cobalt acts as awetting layer for PVD cobalt re-flow.

FIG. 6 depicts a flow diagram for forming a contact metal layer in asemiconductor device in accordance with one embodiment of the presentinvention. The sequence described in FIG. 6 corresponds to thefabrication stages depicted in FIGS. 7A-7E, which are discussed below.FIGS. 7A-7E illustrate schematic cross-sectional views of a substrate402 having a device structure 408 formed thereon during different stagesof fabricating a contact metal layer 420 on the device structure 408illustrated by the processing sequence 600. The sequence of FIG. 6 isgenerally provided with reference to a CVD, ALD, or PVD deposited cobaltcontact metal layer.

Certain aspects of process 600 are similar to process 300 described withreference to FIG. 3 and will not be repeated hereinafter for the sake ofbrevity. In one embodiment, blocks 610 and 620 are similar to blocks 310and 320 depicted in FIG. 3 as described above. Blocks 610 and 620correspond to the fabrication stages depicted in FIGS. 7A and 7B,respectively. A detailed discussion of FIGS. 7A and 7B may be found withreference to FIGS. 4A and 4B. However, performing a pretreatment processon the substrate may be optional in block 620.

Block 630 provides for performing a barrier layer deposition to deposita barrier layer 416 on the substrate 402, as shown in FIG. 7C. Thebarrier layer generally contains a metal or a metal nitride material,such as titanium (Ti), titanium nitride (TiN), alloys thereof, orcombinations thereof. The barrier layer 416 may also comprise plasmanitrided (N₂ or NH₃) Ti and PVD Cobalt. If the barrier layer 416comprises a nitrided Ti layer, only the top few angstroms of titaniumare converted to a TiN compound. It has been found that non-oxidized Tiand TiN barrier layers provide for improved diffusion resistance. Thebarrier layer 416 may have a thickness within a range from about 2 Å toabout 100 Å, more narrowly within a range from about 3 Å to about 80 Å,more narrowly within a range from about 4 Å to about 50 Å, more narrowlywithin a range from about 5 Å to about 25 Å, more narrowly within arange from about 5 Å to about 20 Å, more narrowly within a range fromabout 5 Å to about 15 Å, and more narrowly within a range from about 5 Åto about 10 Å. The barrier layer is generally deposited by atomic layerdeposition (ALD), plasma-enhanced ALD (PE-ALD), chemical vapordeposition (CVD), or physical vapor deposition (PVD) processes.

In one embodiment, performing a barrier layer deposition comprises anALD process comprising providing a Ti containing precursor which may beprovided to the chamber in the presence of a carrier gas, such as aninert gas. In another embodiment, a Ti containing precursor may beprovided with a nitrogen containing precursor to form a barrier layercomprising TiN. The Ti containing precursor and the nitrogen containingprecursor may be provided in the presence of a carrier gas, such as aninert gas. In another embodiment, a nitridation process may be performedon a deposited Ti layer to form a TiN barrier layer. In anotherembodiment, the Ti barrier layer is deposited by a PVD Ti process.

Block 635 provides for performing a wetting layer deposition to deposita wetting layer 718 on the substrate 402, as shown in FIG. 7D. Thewetting layer 718 is deposited over the barrier layer 416. The wettinglayer is generally deposited by a process selected from PVD Co, CVD TiN,PVD TiN, CVD Ru, PVD Ru, nitridation of PVD Ti, or combinations thereof.In embodiments using a CVD process to deposit the wetting layer 718, adesired precursor gas is provided to the chamber and may be furtherprovided in the presence of a carrier gas. In embodiments using a PVDprocess to deposit the wetting layer 718, a target comprising thedesirable material to be deposited is provided and a PVD process isperformed to deposit a PVD wetting layer. In one embodiment, the wettinglayer comprises PVD TiN. In this embodiment, a Ti target is provided andbombarded with ions to sputter Ti to deposit the wetting layer 718 overthe barrier layer 416. A nitridation process using a nitrogen containingprecursor, such as NH₃, in the presence of a plasma is performed on thePVD Ti layer to form the TiN wetting layer 718. In this embodiment, thewetting layer 718 comprises a nitrided Ti layer and only the top fewangstroms of titanium are converted to a TiN compound. In anotherembodiment, the wetting layer is PVD Co. In this embodiment, a Co targetis provided and bombarded with ion to sputter co to deposit the wettinglayer 718 over the barrier layer 416. In the embodiment using PVD Co, RFpower is provided at a frequency from about 5000 W to about 6000 W, suchas about 5500 W. A power of the PVD Co process is provided from about400 W to about 600 W, such as about 500 W and the pressure of thechamber while performing the PVD Co process is from about 50 mT to about150 mT, such as about 100 mT.

It should be known that a wetting layer of Ti or TiN may be deposited inthe same chamber (under high vacuum) as a subsequent CVD Co depositionprocess. In an alternate embodiment, agglomeration of CVD Co filmsduring anneal involved using CVD Co (with different film properties) asa wetting layer. This CVD Co wetting layer included high carbon atomic% >5% carbon compared to <1% carbon for CVD Co films used for gap-fillpurpose. The high carbon content CVD Co films were obtained using lowerH2 partial pressure during deposition step and by eliminating cyclic H2plasma treatment.

It should be noted that any of the aforementioned wetting layer 718processes may be performed with the subsequent contact metal layerdeposition process which is provided at block 640. The wetting layer 718and the barrier layer 416 generally enhance the subsequent contact metallayer deposition. It has been found that voids may form at the bottom ofa feature on the substrate or at other locations in the feature. Thevoids are believed to be formed as a result of agglomeration, or theaccumulation of the contact metal layer, when the contact metal layer isannealed. The voids are generally undesirable because a void between thesubstrate and the contact metal layer ultimately reduces the quality ofthe contact and negatively affects overall device performance. Further,inter-diffusion between the contact metal layer and the underlyingsubstrate during anneal processes result in Co and siliconinter-diffusion. The inter-diffusion negatively affects deviceperformance and leads to unpredictable device behavior. The barrierlayer 416, either alone or in combination with the wetting layer 718,reduces the Co and silicon inter-diffusion. Further, the wetting layer,either alone or in combination with the barrier layer 416, enhances theadhesion of the contact metal layer when it is deposited to fill thevias and trenches of the device by reducing the probability ofagglomeration during subsequent anneal processes.

In an alternate embodiment, agglomeration of CVD Co films during ananneal process may use CVD Co as a wetting layer. This CVD Co wettinglayer may include a high carbon content (atomic % >5%) carbon ascompared to a low carbon content (atomic % <1%) carbon for CVD Co filmsused for seamless gap-fill. The high carbon content CVD Co films wereobtained using lower H2 partial pressure during the deposition step andby eliminating cyclic H2 plasma treatment.

Block 640 provides performing a cyclic metal deposition to deposit acontact metal layer on the substrate. The process parameters anddescription of the cyclic metal deposition process may be found abovewith regard to block 340 in FIG. 3 and the corresponding descriptionrelated to FIG. 5. Block 650 provides for performing an annealingprocess on the contact metal layer disposed on the substrate. Theprocess parameters and description of the performing an annealingprocess may be had with reference to block 350 in FIG. 3.

After the thermal annealing process is completed, at block 660, if thepredetermined thickness of the contact metal layer 420 has not beenachieved, additional cycles starting from performing a cyclic metaldeposition to deposit a contact metal layer at block 640 followed byperforming an annealing process on the contact metal layer at block 650can then be repeatedly performed until a desired thickness range of thecontact metal layer 420 is reached. If the predetermined thickness ofthe contact metal layer has been achieved, the process is complete andadditional processing steps may be performed.

As noted above, process sequence 600 described in FIG. 6, may be hadwith reference to CVD, ALD, or PVD contact metal deposition processes.An integrated (non-oxidized) CVD or ALD TiN barrier layer 418 reducedthe presence of voids at the bottom of the device feature. A vacuumbreak may be introduced after the wetting layer 718 deposition or afterthe contact metal layer 420 deposition before performing the annealprocess of block 650. It should be noted that the anneal process ofblock 650 may be performed in a chamber other than the chamber in whichthe contact metal layer 420 was deposited. Moreover, it was found that ahigh frequency of H₂ plasma treatment (plasma treatment at a CVD Cothickness of 20 Å or less), as provided at block 640 (See FIG. 5 forrelated plasma processing parameters), played a significant role ineliminating void formation at the bottom of the device features.Finally, it has been found that the reflow characteristics of CVD or ALDcontact metal layers may be regulated by controlling the atomic percentof impurities (i.e. carbon, oxygen, nitrogen, etc.) by theaforementioned process variables provided in process sequence 600. A onepercent or lower carbon impurity level may be necessary for enabling aseamless contact metal layer gap-fill, more specifically, a seamlesscobalt gap-fill. In addition to the process variables of the contactmetal layer deposition, the impurity levels may be further controlled bythe barrier layer 418 and the wetting layer 718.

FIG. 8 depicts a flow diagram for forming a contact metal layer in asemiconductor device in accordance with one embodiment of the presentinvention. The sequence described in FIG. 8 corresponds to thefabrication stages depicted in FIGS. 7A-7E, which are discussed below.FIGS. 7A-7E illustrate schematic cross-sectional views of a substrate402 having a device structure 408 formed thereon during different stagesof fabricating a contact metal layer 420 on the device structure 408illustrated by the processing sequence 800. The sequence of FIG. 8 isgenerally provided with reference to a PVD deposited cobalt contactmetal layer.

Processing sequence 800 begins by providing a substrate at block 810. Adetailed description of block 810 may be had by reference to thedescriptions related to blocks 310 in FIG. 3 and block 610 in FIG. 6.Block 820 provides for optionally performing a pretreatment process onthe substrate. Detailed description related to block 820 may be had byreference to the descriptions related to block 320 in FIG. 3 and block620 in FIG. 6.

Block 830 provides performing a barrier layer deposition to deposit abarrier layer on the substrate. A general description regarding thebarrier layer 416 may be had with reference to block 630 in FIG. 6. Inone embodiment, a TiN barrier layer, such as the TiN barrier layer 416described above, is disposed on the substrate. In this embodiment, theTiN layer is provided at a thickness of between about 5 Å and about 75Å, such as about 50 Å. However, it has been shown that a 10 Å TiN layermay be sufficient as a barrier layer. The TiN barrier layer 416 isformed by NH₃ or N₂ nitridation of a previously deposited Ti layer or bya CVD deposition process. Processing parameters for the deposition ofthe TiN barrier layer 416 may be found with regard to block 630 in FIG.6.

Block 835 provides performing a wetting layer deposition to deposit awetting layer on the substrate. A general description of the wettinglayer 718 may be had with reference to block 635 in FIG. 6. In oneembodiment, the wetting layer 718 is deposited by a CVD or ALD process.Suitable processes for providing the wetting layer 718 include CVD TiN,CVD Co, CVD Ru, ALD TaN, and combinations thereof. In one embodiment,the wetting layer may be deposited by a CVD Co process. The cobaltdeposited during the CVD process is provided to the processing chamberby a cobalt containing precursor, such as the cobalt containingprecursors discussed with reference to the cyclic metal depositionprocess provided in FIG. 3. In one embodiment, the cobalt containingprecursor is provided to the chamber in a thermal deposition process.The thermal deposition process generally comprises heating the substrate402 to promote deposition of the cobalt on the surface of the substrate402. In one embodiment, the thermal deposition process provides forheating the substrate from about 100° C. to about 200° C., such as about150° C. In this embodiment, the cobalt deposited during the CVD Coprocess is the wetting layer 718 which is disposed over the barrierlayer 416.

Block 840 provides for performing an annealing process on the wettinglayer 718. The annealing process is generally performed to reduce thesurface roughness of the wetting layer 718, increase grain size of thecrystalline structure, and reduce impurities, such as carbon, that maybe present in the wetting layer 718. The annealing process is performedat a temperature of between about 200° C. to about 500° C., such asabout 400° C. The annealing process may be performed in a chamberenvironment where an inert gas, such as argon, is provided in thechamber. In one embodiment, argon gas is static within the chamber andthe chamber may be optionally purged after the annealing of the wettinglayer 718 is performed. In one embodiment, the annealing process isperformed for a duration of between about 10 seconds to about 1000seconds, such as between about 30 seconds and about 90 seconds, such asabout 60 seconds. In another embodiment, the annealing process may beperformed in a chamber environment where H₂ gas is provided to thechamber in a static or flowing manner. In this embodiment, the annealingprocess may be performed for a duration of between about 10 seconds toabout 1000 seconds.

Block 850 provides for performing a metal deposition process fordepositing a contact metal layer 420 on a substrate. In one embodiment,the contact metal layer 420 is deposited by a PVD Co process. The PVD Coprocess may further be a thermal PVD Co process. The cobalt is sputteredusing conventional processes, and in one embodiment, the sputteringprocess is performed in the presence of a process gas, such as argon orH₂. In one embodiment, the PVD Co process may be performed by providingRF power at a frequency from about 5000 W to about 6000 W, such as about5500 W. The RF may be provided in a direct current at a power of betweenabout 250 W and about 750 W, such as about 500 W. The pressure of thechamber during the PVD Co process may be maintained at a pressure ofbetween about 50 mTorr and about 200 mTorr, such as about 100 mTorr.Once the cobalt has been sputtered to the substrate, the cobalt may bereflowed by providing heat to the substrate to reflow the as depositedcobalt. In one embodiment, the PVD Co reflow may be performed by heatingthe substrate to a temperature of between about 200° C. to about 500° C.In embodiments where a PVD Co process is employed, both the contactmetal layer 420 deposition and anneal may be performed in the samechamber if the chamber has the capability to heat the substrate totemperatures required for processing.

Block 860 provides for exposing the contact metal layer 420 to a plasmatreatment process. The plasma treatment process generally comprisesproviding a process gas, such as H₂, to the chamber and applying an RFcurrent to form the process gas into a plasma. In one embodiment, thefrequency of the RF current is provided between about 200 W and about800 W, such as about 400 W. The plasma treatment process is performedfor about 1 second to about 60 seconds, such as about 30 seconds. In oneembodiment, the substrate 402 may be heated to a temperature of betweenabout 100° C. to about 200° C., such as about 150° C. to further reducethe surface roughness of the contact metal layer 420 and reduce thepercentage of impurities that may be present in the contact metal layer420.

Block 870 provides for performing an annealing process on the contactmetal layer 420 disposed on the substrate 402. The annealing process isgenerally performed to reduce the surface roughness of the contact metallayer 420 and reduce impurities, such as carbon, that may be present inthe contact metal layer 420. Further the annealing process increasescrystalline grain size which results in lower resistivity, resulting inimproved integrated circuit performance. The annealing process isperformed at a temperature of between about 200° C. to about 500° C.,such as about 400° C. The annealing process is further performed in achamber environment where an inert gas, such as argon, and a processgas, such as H₂, are provided in the chamber. In one embodiment, argonand H₂ gas are flowing within the chamber and the chamber may beoptionally purged after the annealing of the contact metal layer 420 isperformed. In one embodiment, the annealing process is performed betweenabout 30 seconds and about 90 seconds, such as about 60 seconds.

In the embodiments above, the PVD Co process may be performed without acyclic metal deposition process if the Co deposition and anneal processare performed in a chamber that provides for heating the substrate. Inan alternative embodiment, a PVD Co layer may be deposited at the bottomof a feature and may be etched and re-sputtered on the feature side wallto provide a continuous cobalt film on the side wall which allows forreflow of the PVD Co from the field to the bottom of the feature. Thecontact metal layer 420 deposition is performed to obtain a sufficientfilm thickness required for a subsequent chemical mechanical polish ofthe contact metal layer 420.

In another embodiment, the contact metal layer 420 deposited after a CVDCo wetting layer 718 may comprise tungsten (W). This embodiment isgenerally used with a dual damascene type structure having a lower partof the feature exhibiting a small critical dimension and aggressiveaspect ratio. The upper portion of the dual damascene type structuregenerally has a greater critical dimension and less aggressive aspectratio when compared to the lower portion. In this embodiment, the lowerportion, which presents additional contact metal layer depositionchallenges, may be filled with a CVD Co process as described above. TheCVD Co process fills the lower portion of the feature. Following the CVDCo deposition, a CVD W process may be performed to fill the remainingportion of the feature. The CVD W process generally deposits material ata faster rate than the CVD Co process, thus allowing for increasedthroughput.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

The invention claimed is:
 1. A method for depositing a contact structurein a semiconductor device, comprising: performing a cyclic metaldeposition process to deposit at least part of a gate electrode inopenings formed on a silicon containing substrate, the at least part ofthe gate electrode comprising a cobalt contact metal adjacent a metalcontaining layer, the cyclic metal deposition process comprising:exposing the substrate to a deposition precursor gas mixture to deposita portion of the cobalt contact metal on the substrate; exposing theportion of the cobalt contact metal to a plasma or thermal treatmentprocess; and repeating the exposing the substrate to a depositionprecursor gas mixture and the exposing the portion of the cobalt contactmetal to a plasma or thermal treatment process until a predeterminedthickness of the cobalt contact metal is achieved; and annealing theportion of the cobalt contact metal disposed on the substrate.
 2. Themethod of claim 1, wherein the deposition precursor gas mixture includesa cobalt containing precursor and a reducing gas.
 3. The method of claim2, wherein the cobalt containing precursor is dicobalt hexacarbonylbutylacetylene (CCTBA) and the reducing gas is hydrogen (H2).
 4. Themethod of claim 1, further comprising: supplying a pretreatment gascomprising NH3to pretreat the substrate prior to the performing a cyclicmetal deposition process.
 5. The method of claim 1, wherein the exposingthe substrate to a deposition precursor gas mixture to deposit a portionof the cobalt contact metal on the substrate and the exposing theportion of the cobalt contact metal to a plasma or thermal treatmentprocess are performed simultaneously.
 6. The method of claim 1, whereinthe exposing the portion of the cobalt contact metal to a plasma orthermal treatment process comprises supplying a gas selected fromhydrogen (H₂), nitrogen (N₂), ammonia (NH₃), and combinations thereof toreduce roughness of the portion of the cobalt contact metal.
 7. A methodfor depositing a contact metal layer for forming a contact structure ina semiconductor device, comprising: performing a barrier layerdeposition process to deposit a barrier layer on a substrate; performinga wetting layer deposition process to deposit a wetting layer on thebarrier layer; performing an annealing process on the deposited wettinglayer; performing a PVD metal deposition process to deposit a contactmetal layer on the deposited wetting layer by exposing the wetting layerto a process gas to deposit a portion of the contact metal layer on thesubstrate, wherein the performing the PVD metal deposition processcomprises depositing a PVD Co layer, wherein the PVD Co layer issputtered onto the substrate at a temperature of between about 200° C.and about 500° C., an RF power of between about 5000W and 6000W, and aprocess chamber pressure of between about 50 mTorr and about 200 mTorr;and annealing the deposited PVD Co layer and the deposited wetting layerformed on the substrate.
 8. The method of claim 7, wherein the barrierlayer is deposited to a thickness of between about 5 Å and about 75 Å.9. The method of claim 7, wherein the barrier layer is an ALD TiNbarrier layer.
 10. The method of claim 7, wherein the performing awetting layer deposition process comprises depositing a non-oxidized Tior TiN layer, a CVD Co layer, or a PVD Co layer.
 11. The method of claim10, wherein the CVD Co layer is deposited by a thermal depositionprocess.
 12. The method of claim 11, wherein the substrate is heated toa temperature of between about 100° C. and about 200° C. during thethermal deposition process.
 13. The method of claim 7, wherein theperforming a wetting layer deposition process comprises depositing a CVDTiN layer, a CVD Ru layer, an ALD TaN layer, and combinations thereof.14. The method of claim 7, wherein the wetting layer annealing processis performed at a temperature of between about 200° C. and about 500° C.and for a duration of between about 30 seconds and about 90 seconds. 15.The method of claim 14, wherein the wetting layer annealing process isperformed in an argon or hydrogen containing chamber environment. 16.The method of claim 15, wherein the chamber environment is purged afterperforming the wetting layer annealing process.
 17. A method fordepositing a contact metal layer for forming a contact structure in asemiconductor device, comprising: performing a barrier layer depositionprocess to deposit a barrier layer on a substrate, the performing abarrier layer deposition process comprising depositing a barrier layer;performing a wetting layer deposition process to deposit a wetting layeron the barrier layer; performing an annealing process on the wettinglayer; performing a cyclic metal deposition process to deposit at leastpart of a gate electrode in openings formed on a silicon containingsubstrate, the at least part of the gate electrode comprising a cobaltcontact metal adjacent a metal containing layer, the cyclic metaldeposition process comprising: exposing the substrate to a depositionprecursor gas mixture to deposit a portion of the cobalt contact metalon the substrate; exposing the portion of the cobalt contact metal to aplasma or thermal treatment process; and repeating the exposing thesubstrate to a deposition precursor gas mixture and the exposing theportion of the cobalt contact metal to a plasma or thermal treatmentprocess until a predetermined thickness of the cobalt contact metal isachieved; and annealing the portion of the cobalt contact metal disposedon the substrate.
 18. The method of claim 17, wherein the performing abarrier layer deposition process comprises depositing an ALD TiN wettinglayer.
 19. The method of claim 17, wherein annealing the cobalt contactmetal disposed on the substrate occurs at a temperature of about 400° C.